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(No Model.) 2 sheets -Sheet 1-.

P. WRIGHT.

TELEPHONE.

No. 390,428. Patented Oct. 2, 1888.

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P, WRIGHT.

TELEPHONE.

No. 390,428. Patented Oct. 2,1888.-

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By .151 ttorneys N PETERS. Prmwumo n hu. wuhin wn. D. c.

PARVIN WRIGHT, OF DENVER, COLORADO, ASSIGNOR OF SEVENTY ONE- HUNDREDTHS TO PETER O. HORN AND OEOELTA R. NORTHROP, BOTH OF SAME PLACE.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 390,428, dated October 2, 1888.,

Application filed March 6, 1888.

To all whom it may concern:

Be it known that I, PAR'VIN WRIonr, a citizen of the United States, residing at Denver, county of Arapahoe, State of Colorado, have invented certain new and useful Improvements in Telephones, of which the following is a specification.

The object of my invention is to provide an improved telephone capable of transmitting speech with large volume, great distinctness, and sufiicient energy to work on long lines.

Briefly stated, my invention consists in providing a telephone with an electromagnet the coils of which are included in an electric circuit, and providing resistance devices in an independent circuit operated upon in an improved way by the electro-magnet to vary their conductivity. This organization of apparatus may be employed in connection with a telephone-transmitter by including in the ordinary local circuit of the transmitter an electro-magnet adapted to act upon the resistance devices in an independent circuit, which may constitute the main line,or which may include the primary of an induction-coil.

A telephone-receiver may embody my invention by having an eleetro-magnet adapted to act upon resistance devices arranged in an independent circuit which includes a local battery and the electro-magnet for vibrating the diaphragm.

My invention may also be used in a telephone-relay by connecting the coils of an electro-magnet to themain line, providing re sistance devices acted upon by the electromagnet, and including the resistance devices in an independent circuit.

In the accompanying drawings, illustrating my invention, Figure l is a view, partly in section, of a telephonetransmitter embodying my invention, showing also an inductioncoil and the electric-circuit connection. Fig. 2 is a section of a telephone-receiver with myim provements applied, showing also the circuitconnections. Fig. 3 shows in section a telephonerelay embodying my improvements, and also the electric-circuit connections with the main line and a telephonereceiver. Fig. 4 is an end view of a transmitting-telephone, showing a number of mouth-pieces.

Serial No. 266,347. (No model.)

Referring first to Fig. 1.of the drawings, which illustrates a telephone-transmitter embodying myinvention, A indicates the mouthpiece of the telephone, B the diaphragm, and O the frame or casing, all of which may be of any desired construction. D indicatcsaspring carrying an electrode, (1, in contact with the diaphragm,and with an electrode or button, E, of some substance capable of variable electrical resistancecarbon, for instance. The local circuit F, having a battery, G, includes the electrodes E (Z. The local circuit F also includes the coils of an electromagnet, H, mounted in suitable supports in the frame 0; or it may be located ata distance,if desired,and-operatively connected with the transmitting-diaphragm by the circuit F. The magnet is preferably provided with a hollow core, I, through which extends a rod, J,secured at one end to the armature K and at the other end to a metallic plate, L. The core of the magnet projects from the coil and bears upon the plate L. N and 0 indicate resistanceblocks, preferably carbon, with a layer between them of powdered carbon and eaoutchouc or other semiconducting material, 0, capable of variable electrical resistance. The block 0 rests on a metallic plate, 1?, and against this. block bears a set-screw, Q, mounted in the frame, and which may be used to adjust the blocks relatively to the armature K, and also vary the pressure between the blocks upon the powdered material, 0. Uindicates a rubber band stretched around the plates and blocks, serving to hold them in position, and also to retain the powdered material, 0. Those parts of the frame 0 which support electrical conductors included in the electric circuits are preferably made of non-conducting material.

The terminals of a battery-circuit, R, are electrically connected with the plates L and P, as shown, and thus include the resistanceblocks N and O and the powdered material, 0, in the circuit. The circuit B may be used as the main-line circuit, or it may include the primary of an induction'coil, S, the secondary of which includes the main line, as shown in the drawings.

It will be seen that the resistance device operated upon by the magnet His separate and distinct from the usual resistance or electrode devices of the transmitter-diaphragm.

-When the diaphragm B is vibrated by airwaves, the current in the local circuit F will be varied and will produce corresponding variations in the elcctro-magnet H, thereby causing the core I to correspondingly expand and contract or lengthen and shorten, and also causing the armature K to vibrate coincidently with the transmitting-diaphragm. The expansion and contraction of the core and the vibrations of the armature cause corresponding variations in the pressure between the resistance-blocks N and O and the interposed semi-conducting material, 0; but the effect is multiplied, as the contact-surface of the blocks is much larger than the contact-surface in the local transmitting-circuit F, and the mechanical force used to vary the pressure between the resistance-blocks in the second circuit, R, is enabled to control a much stronger battery in this circuit R, so that a large volume of sound is transmitted, and it is made clear and distinct at the receiving end of the line.

As above remarked, the electro-magnet, its armature, and the resistance-blocks need not be located in the,frame 0. As is indicated, by breaking away the frame G at c, Fig. 1, it may be made in two portions or separate structures, which may be located at any desired distance apart preferred and operatively connected with the transmitting-diaphragm by the circuit F. By multiplying. the apparatus, as shown in Fig. 4, an increased effect is produced. Sounds taken up by the transmitter may be carried to different places over different lines; or the apparatus may be so arranged that the different transmitters may connect with the same main line.

Obviously other modifications may be made in the apparatus. The number of diaphragms, electro-magncts, and resistance devices may be increased, diminished, or varied at pleasure.

In connection with my improved transmitting apparatus I may employ a receiving-telephone so constructed as not to be affected by induced currents or statidal electricity. This I accomplish by removing the diaphragm a suitable distance from the core of the magnet, so that it will be less sensitive and out of the reach of external influenees,and still be within the strong magnetic field derived from myimproved transmitter.

Referring now to Fig. 2 of the drawings, which illustrates my invention embodied in a telephone-receiver, Aindicates the casing; B, the ordinary diaphragm; O, the electro-magnet for vibrating the diaphragm. D indicates a supplemental elective-magnet contained within the casing A, and having a core, E, rigidly secured at its inner end to the casing by means of setscrew F. It may also be secured to the core G of the electro-magnet O by a set-screw, H. a 1) indicate carbon blocks; 0, powdered carbon and caoutchouc or similar semi-conducting material between the carbon blocks; (1, a metallic plate, against which bears the core E of the magnet D; c, a metallic plate which rests against the outer face of the carbon block b. H indicates a set-screw, which bears against the lower plate, 6, and serves to adjust the blocks relatively to each other and to compress the powdered material between the blocks.

:0 indicates the main line, which includes the electro-magnet D, as indicated. 9 indicates a local circuit, including a battery, Y, and the resistance devices, as indicated. As will be seen, the circuit y is electrically connected with electro-magnet G and includes it in the circuit.

The operation of the receiver is similar to the operation of the transmitter-that is, the main-line current energizes the electro-magnet D. This causes the core E to expand and contract, or lengthen and shorten, and thereby vary its pressure on the plate 61, and consequently the pressure on the carbon blocks and the interposed powdered material. This variation in pressure varies the local circuit correspondingly to the variations in the mainline circuit, and consequently produces a corresponding variation in the electro-magnet O, causing it to vibrate the diaphragm B, to produce sound-waves similar to those produced at the transmitting end of the line.

Fig. 3 illustrates my improved telephone-relay. I indicates the rigid frame or casing; K, an electro-magnet securely fastened at L to the casing. Mindicates the core of the magnet, also rigidly secured to the casing at L, as shown. f and 9 indicate carbon blocks, between which may be arranged powdered carbon or similar material. h and indicate metallic plates on the outer faces of the carbon blocks. The screw N may be arranged to bear against the plate 13 to regulate the pressure between the blocks. Z indicates the main-line circuit, which includes the electromagnet K. X indicates an independent circuit, including a battery, Y. This circuit may be of any desired length. It is shown as connected with atelephonereceiver, O, sufficiently apart from the magnet K and the resistance device 0perated by expansion and contraction of this magnets core. This apparatus works on the same principle as that described in connection with Figs. 1 and 2. The elongation and contraction of the core of the magnet K varies the pressure on thejcarbon blocks and correspondingly varies the current in the independent circuit.

In Fig. 4. is shown a telephonetransmitter, in which several mouth-pieces are arranged in close proximity to each other. These may either be provided with their corresponding electro magnetic devices for transmitting speech to different points or the local circuits may be united in a single main-line circuit for increasing the volume and distinctness of sound transmitted.

Although it is not new, broadly considered, to combine in telephone apparatus an electromagnet having a projecting elongating and contracting core and a resistance device operated by elongation and contraction of said core, I am not aware of any apparatus of this class prior to my invention in which such magnets have been mounted or arranged in frames in which the resistance devices are also arranged, with the cores of the magnets operating upon the resistance devices, as above described and hereinafter claimed.

Having thus described my invention, I. claim- 1. The combination, in a telephone apparatus, of the circuit operated by the transmitter and including a battery and the coils of an electro-magnet provided with a projecting elongating and contracting core, the framein which the magnet is supported, the armature located in said frame at one end of said core, the resistance device located in said frame at the opposite end of the core and directly operated upon by the magnet by elongation of its core, and a second circuit including a battery and the said resistance device, substantially as set forth.

2. The combination of the receiver provided with the diaphragm, the circuit including a battery and an electro-magnet for vibrating the receiver-diaphragm, and the main line or second circuit including the coils of a supplemental electro-magnet having a projecting core and operating the electro-magnet for vibrating the receiver-diaphragm, and the resistance device against which said core bears, substantially as set forth.

3. The combination of the main-line circuit including the electro-magnet with the projecting elongating and contracting core, the rigid frame in which the magnet and its core are mounted and secured at one end, the resistance device at the opposite end of said frame and directly operated upon by the magnet by the elongation of its core, and theindependent or local circuit including said resistance device and a battery, and the receiver with which said local circuit is connected, substantially as set forth.

In testimony whereof I have hereunto sub scribed my name.

PARVIN WRIGHT. 

